From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 41AAF606A321 for ; Thu, 12 Nov 2026 21:07:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=kDWacs87 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=KPcGxWktlaGg63UoR245IUkJTtv/C1wkP9UzgLCl4Ro=; b=kDWacs87X2iIYd5baEZzgq1MCj QvccjxrMNVAmrG+/DSpbSDkhyqEW8pWcEy4VAIJEFUHZA+OFQ26i5CE2OiHu3XxZzlBY4CapegHCN E3ffmb7821qguSxYv4oPd1n2wRb4Xuatt2l/fzJIOl2/LjJC66dOak94/eKf7bOk4sRVTmhrBvuoy JvTsyME0/nqEYFk0uGLTNrg1cQlZBgRoHflfyuErb8BboO/wXIdUpbqymYdM83WffMWEF2tffryeA 2rUJ5wcIsZHII3A8GOIXEvI4PD/f4wDv4rK/wzV9wGy32RGJ4wMzpbhzBH3VvJ720va1EQNdR0Epd AWbBPR8A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRc15-0000000B3ER-1Oiz; Thu, 12 Nov 2026 21:07:31 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRc12-0000000B3DN-15DI for linux-nvme@lists.infradead.org; Thu, 12 Nov 2026 21:07:30 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 12F196732A; Thu, 12 Nov 2026 22:07:19 +0100 (CET) Date: Thu, 12 Nov 2026 22:07:18 +0100 From: Christoph Hellwig To: Paul Menzel Cc: Bjorn Helgaas , dlemoal@kernel.org, cassel@kernel.org, kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Alexey.Bogoslavsky@sandisk.com Subject: Re: [PATCH RFC] PCI: Start the reset of WD PC SN730 NVMe controllers early Message-ID: <20261112210718.GA11040@lst.de> References: <20261111163145.75027-2-pmenzel@molgen.mpg.de> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261111163145.75027-2-pmenzel@molgen.mpg.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261112_130728_452932_4A7F698B X-CRM114-Status: GOOD ( 15.33 ) X-Spam-Score: -1.9 (-) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" X-Spam-Status: No, score=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, Nov 11, 2026 at 05:31:43PM +0100, Paul Menzel wrote: > devmem, works: the driver finds CSTS.RDY clear and continues, the reset > completed within the first poll in 29 of 30 boots (35 polls once), and > none of the 30 boots showed a slow reset, enable or read, against 8 of > 90 without it. The difference is not yet significant (p = 0.1). > > So start the reset in a final fixup during enumeration, at 0.19 s on > this machine, about 100 ms before nvme probes, which overlaps a slow > reset with the remaining kernel initialization and the module loading, > and costs nothing for fast ones. Umm, no. PCI quirks are not a way to speed up slow device initialization, which while annoying is not a bug per se.